Communication system, communication method, and recording medium recording communication program

ABSTRACT

In a communication system in which a plurality of master stations wirelessly communicate with a plurality of slave stations in a predetermined cycle, each of the plurality of slave stations being associated with one of the plurality of master stations, and the communication system includes: an allocation processor that allocates the plurality of master stations respectively to a plurality of temporal intervals resulting from time-division of the predetermined cycle, in a predetermined channel; and a communication processor that, in each of the plurality of temporal intervals, causes the master station to communicate with a plurality of slave stations associated with the master station, within that temporal interval.

INCORPORATION BY REFERENCE

This application is based upon and claims the benefit of priority fromthe corresponding Japanese Patent Application No. 2022-015592 filed onFeb. 3, 2022, the entire contents of which are incorporated herein byreference.

BACKGROUND

The present disclosure relates to a communication system, acommunication method, and a recording medium recording therein acommunication program.

Such a communication scheme (time division multiple access:TDMA) hasbeen known, in which one master station (also referred to as“controller” or “host”) occupies a single channel, and sequentiallycommunicates with a plurality of slave stations (also referred to as“slave”) allocated to the master station, in a time-division manner.Each slave station is allocated with a certain time which is immediatelyafter reception of communication (transmission data) from the masterstation, as a time communicable with a host.

In factories and warehouses, etc., operators perform picking operationsto pick articles stored in storage shelves. A picking system to optimizethe picking operations has been introduced. In the picking system, aplurality of storage shelves, a slave station (tag having acommunication function) provided for each storage shelf, and a masterstation (controller) to control the plurality of tags are provided in anoperation area. The controller transmits a command (which may include alighting instruction) to a tag of a storage shelf in which an article tobe picked is stored, and lights a lamp (LED) provided for the tag. Anoperator picks a target article from the storage shelf whose lamp islit.

High-speed responsiveness is required of the aforesaid picking system;however, conventional technologies can only maintain limited levels ofhigh-speed responsiveness while deploying a multitude of slave stationsin wider areas and increasing the communication amount. Usage of amultitude of channels by dividing frequencies so as to deploy amultitude of slave stations in wider areas is possible; however, if thenumber of channels is limited, communication with a multitude of slavestations, while maintaining high-speed responsiveness, is difficult.

An object of the present disclosure is to provide a communicationsystem, a communication method, and a recording medium recording thereina communication program, according to which a multitude of slavestations can be deployed while maintaining high-speed responsiveness incommunication between a master station and a slave station.

SUMMARY

In a communication system according to an embodiment of the presentdisclosure, a communication system, a plurality of master stationswirelessly communicate with a plurality of slave stations in apredetermined cycle. The communication system includes an allocationprocessor and a communication processor. Each of the plurality of slavestations being associated with one of the plurality of master stations.The allocation processor allocates the plurality of master stationsrespectively to a plurality of temporal intervals resulting fromtime-division of the predetermined cycle, in a predetermined channel.The communication processor, in each of the plurality of temporalintervals, causes the master station to communicate with a plurality ofslave stations associated with the master station, within that temporalinterval.

In a communication method according to an embodiment of the presentdisclosure, a plurality of master stations wirelessly communicate with aplurality of slave stations in a predetermined cycle. Each of theplurality of slave stations being associated with one of the pluralityof master stations. The communication method causing one or a pluralityof processors to perform: an allocation step of allocating the pluralityof master stations respectively to a plurality of temporal intervalsresulting from time-division of the predetermined cycle, in apredetermined channel; and a communication step of causing the masterstation to, in each of the plurality of temporal intervals, communicatewith a plurality of slave stations associated with the master station,within that temporal interval.

A recording medium according to an embodiment of the present disclosurerecords therein a communication program by which a plurality of masterstations wirelessly communicate with a plurality of slave stations in apredetermined cycle. The communication program causes one of a pluralityof processors to perform an allocation step and a communication step.Each of the plurality of slave stations is associated with one of theplurality of master stations, and the allocation step allocates theplurality of master stations respectively to a plurality of temporalintervals resulting from time-division of the predetermined cycle, in apredetermined channel. The communication step causes the master stationto, in each of the plurality of temporal intervals, communicate with aplurality of slave stations associated with the master station, withinthat temporal interval.

The present disclosure provides a communication system, a communicationmethod, and a recording medium recording therein a communicationprogram, according to which a multitude of slave stations can bedeployed while maintaining high-speed responsiveness in communicationbetween a master station and a slave station.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription with reference where appropriate to the accompanyingdrawings. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Furthermore,the claimed subject matter is not limited to implementations that solveany or all disadvantages noted in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram illustrating an overallconfiguration of a communication system according to an embodiment ofthe present disclosure.

FIG. 2 is an external view of a storage shelf according to an embodimentof the present disclosure.

FIG. 3 illustrates a configuration of a tag provided for a storage shelfaccording to an embodiment of the present disclosure.

FIG. 4 illustrates an example of tag information stored in a storage ofthe communication system, according to an embodiment of the presentdisclosure.

FIG. 5 illustrates an example of association information stored in thestorage of the communication system, according to an embodiment of thepresent disclosure.

FIG. 6 illustrates a correspondence relationship between controllers andtags, according to an embodiment of the present disclosure.

FIG. 7 illustrates an example of temporal intervals allocated tocontrollers according to an embodiment of the present disclosure.

FIG. 8 illustrates a specific example of a communication methodaccording to an embodiment of the present disclosure.

FIG. 9 illustrates a specific example of a communication methodaccording to an embodiment of the present disclosure.

FIG. 10 is a flowchart for explaining an exemplary procedure ofcommunication processing executed in the communication system accordingto an embodiment of the present disclosure.

FIG. 11 illustrates a correspondence relationship between controllersand communication areas according to an embodiment of the presentdisclosure.

FIG. 12 illustrates how each of a plurality of controllers is allocatedto a respective channel and temporal interval, according to anembodiment of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, the embodiments of the present disclosure are describedwith reference to the accompanying drawings. The following embodimentsare examples in which the present disclosure are embodied, but, innature, do not limit the technical scope of the present disclosure.

FIG. 1 is a functional block diagram illustrating an overallconfiguration of a communication system 10 according to an embodiment ofthe present disclosure.

The communication system 10 includes a management server 1, a controller2, and a tag Tg. For example, the communication system 10 is introducedin a work site (such as factory and warehouse) where an operator picks atarget article from a storage shelf 3 (refer to FIG. 2 ) storingarticles. The articles are not particularly limited, and includearticles of various fields, such as parts, retail goods, drugs, books,documents, and miscellaneous goods. In the present embodiment, partsused in assembling a predetermined product (such as vehicle and electricappliance) are taken as an example of the articles. In other words, thecommunication system 10 in the present embodiment is introduced in afacility F1 (such as factory) where an operator picks a target articlefrom the storage shelf 3 storing such parts.

The management server 1 and a controller 2 are connected to each othervia a network N1. The network N1 is a communication network such as theInternet, a local area network (LAN), a wide area network (WAN), or apublic telephone line. A controller 2 and a tag Tg are connected to eachother in the present communication method which utilizes radio waves.The tag Tg is provided in each storage space 31 (refer to FIG. 2 ) ofthe storage shelf 3. As illustrated in FIG. 3 , a tag Tg includes adisplay (LCD) displaying a part's name, etc.; a lamp button B1 forlighting, flashing, and lighting out in a plurality of colors; and acommunicator (not illustrated) communicating with the controller 2. Thelamp button B1 has a button function, as a user interface. The tag Tgcan cause a display to display predetermined information and cause thelamp button B1 to perform lighting and lighting out, according to aninstruction (transmission data) from the controller 2. For example, theoperator picks a part from the storage space 31 in which the tag Tg,whose lamp button B1 is lit, is provided. The tag Tg notifies thecontroller 2 in the present communication scheme that the lamp button B1has been pushed, and the controller 2 notifies the management server 1thereof. If the tag Tg corresponds to an intended part, the managementserver 1 sends, using the present communication scheme and via thecontroller 2, a signal to a tag Tg corresponding to a part to be takenout next, to prompt the lamp button B1 of the tag Tg to flash in apredetermined cycle. FIG. 3 illustrates a state in which a tag 1 is lit.The management server 1 collectively controls the controllers 2, andoutputs, to a predetermined controller 2, a transmission instruction totransmit transmission data (such as a lighting instruction for lightinga tag Tg), based on the information on a target to be picked.

A plurality of storage shelves 3 are provided in the facility F1. Aplurality of controllers 2 are dispersed in the facility F1, and theplurality of the controllers 2 communicate with the tags Tg in theplurality of storage shelves 3 provided in the facility F1. In this way,the communication system 10 constructs a picking system of the facilityF1, by causing the plurality of controllers 2 to control the pluralityof tags Tg provided in the facility F1. Specifically, the communicationsystem 10 is a system managing so that radio wave communication betweenthe plurality of controllers 2 and the plurality of tags Tg is performedin a predetermined cycle.

The management server 1 functions as a mediating station that managesand controls the controllers 2, each controller 2 functions as a hostdevice, and each tag Tg functions as a slave device. The controller 2 isan example of a master station according to the present disclosure, andthe tag Tg is an example of a slave station according to the presentdisclosure.

Management Server 1

As illustrated in FIG. 1 , the management server 1 includes acontrolling part 11, a memory 12, an operational display 13, and acommunicator 14, or the like. For example, the management server 1 maybe an information processor such as a personal computer. The managementserver 1 may also be configured by a cloud server.

The communicator 14 connects the management server 1 to the network N1,in a wired or wireless manner, and performs data communication with thecontroller 2 via the network N1, according to a predeterminedcommunication protocol.

The operational display 13 is a user interface that includes a display,such as a liquid crystal display and an organic electro-luminescence(EL) display, which displays various types of information; and anoperation acceptor, such as a touch panel, a mouse, or a keyboard, to beoperated.

The memory 12 is a non-volatile memory, such as a hard disk drive (HDD),a solid state drive (SSD), and a flash memory, for storing various typesof information. The memory 12 stores such data as tag information D1 andassociation information D2.

FIG. 4 illustrates an example of tag information D1. The tag informationD1 has recorded therein information related to all the tags Tg providedin the facility F1. Specifically, the tag information D1 includes suchinformation as a tag ID, position information, a part's name, etc. Thetag ID is identification information of a tag Tg. The positioninformation is information on a position in which a tag Tg is provided,which is, for example, information on a position of the storage shelf 3,a shelf number allocated to the storage shelf 3 (storage space 31), andcoordinates of the facility F1 on a map. The part's name is a name of apart stored in the storage space 31 provided with the tag Tg.

The tag information D1 is registered by a manager of the facility F1,for example. The tag information D1 may be stored in a server differentfrom the management server 1.

FIG. 5 illustrates an example of association information D2. Theassociation information D2 is information to identify tags Tg associatedwith each of the plurality of controllers 2. Specifically, theassociation information D2 includes information such as a controller IDand a tag ID. The controller ID is identification information foridentifying a controller 2, and the tag ID is identification informationfor identifying tags Tg. Note that, in reality, the most stable tags Tgin communication are associated with each controller 2, and therefore,the IDs of the tags Tg do not have any regularity but are random.

As illustrated in FIG. 6 , a plurality of tags Tg are associated with asingle controller 2. Each controller 2 can communicate with theplurality of tags Tg, and each tag Tg can communicate with a singlecontroller 2. For example, a controller A can communicate with tags Tgwithin a communication area AR1, and a controller B can communicate withtags Tg within a communication area AR2. Note that, in reality, a singletag Tg enters the communication areas AR of a plurality of controllers 2in many cases, as illustrated in FIG. 11 , to expect sufficientcommunication stability. Each tag Tg is associated with the controller 2which is most stable in communication, among these plurality ofcontrollers 2; as a result, in the areas illustrated in FIG. 11 , theradio waves of the plurality of controllers 2 interfere with oneanother. In the present embodiment, five controllers 2 (i.e.,controllers A to E) cover the entire operation area of the facility F1,and can communicate with all the tags Tg in the facility F1. Theassociation information D2 is registered by the later-describedprocessing of the controlling part 11.

The memory 12 may also store picking information, which includes anorder in which parts are taken out, for example. The picking informationhas registered therein, for each part to be picked, information on a tagID, position information, and picking circumstances. The managementserver 1 registers information on a picking target in the pickinginformation, on the basis of a picking instruction. Note that themanagement server 1 may obtain the picking instruction from a serverwhich manages a manufacturing process of a product, or may generate thepicking information, based on the manufacturing process stored in thememory 12.

The memory 12 also stores a control program, such as a communicationprogram, for causing the controlling part 11 to execute later-describedcommunication processing (refer to FIG. 10 ). For example, thecommunication program is non-temporarily stored in a computer-readablerecording medium such as a compact disc (CD) or a digital versatile disc(DVD), and is read by a reader (not illustrated), such as a CD drive ora DVD drive, which is electrically coupled to the management server 1,to be stored in the memory 12.

The controlling part 11 has a controlling device such as a centralprocessing unit (CPU). The CPU is a processor which executes varioustypes of arithmetic processing. The controlling part 11 controls themanagement server 1 by executing, by means of the CPU, the various typesof control programs stored in the memory 12 in advance.

Specifically, the controlling part 11 includes various types ofprocessors, such as an association processor 111, an allocationprocessor 112, communication processor 113. Note that the controllingpart 11 functions as the various types of processors, by executing, bymeans of the CPU, various types of processing according to thecommunication program. A part or all of the processors included in thecontrolling part 11 may be configured by an electric circuit. Thecommunication program may be a program to cause a plurality ofprocessors to function as the various types of processors.

The association processor 111 associates each of the plurality of tagsTg, with one of the plurality of controllers 2.

For example as illustrated in FIG. 5 , the association processor 111associates a plurality of tags Tg having tag IDs “tg0001 to tg0100”provided in a communication area AR1, with a controller A having acontroller ID “c0001” provided in the communication area AR1. Theassociation processor 111 associates a plurality of tags Tg having tagIDs “tg0101 to tg0200” provided in a communication area AR2, with acontroller B having a controller ID “c0002” provided in thecommunication area AR2. The association processor 111 associates aplurality of tags Tg having tag IDs “tg0201 to tg0300” provided in acommunication area AR3, with a controller C having a controller ID“c0003” provided in the communication area AR3. The associationprocessor 111 associates a plurality of tags Tg having tag IDs “tg0301to tg0400” provided in a communication area AR4, with a controller Dhaving a controller ID “c0004” provided in the communication area AR4.The association processor 111 associates a plurality of tags Tg havingtag IDs “tg0401 to tg0500” provided in a communication area AR5, with acontroller E having a controller ID “c0005” provided in thecommunication area AR5.

Note that the above-described association is performed by associatingeach tag Tg with the most stable controller 2 for the tag Tg, andthereafter assigning numbers as necessary. In the present disclosure,each of the plurality of slave stations may be associated with one ofthe plurality of master stations, in advance.

The association processor 111 registers the information on thecontrollers 2 and the tags Tg, associated with one another, in theassociation information D2 (refer to FIG. 5 ).

The allocation processor 112 allocates each of the plurality ofcontrollers 2 to one of the temporal intervals (time slot) resultingfrom time-dividing a predetermined cycle, in a predetermined channel.For example as illustrated in FIG. 7 , when a cycle is “C1”, the cycleC1 is divided into a plurality of temporal intervals. Here, the cycle C1is assumed to be divided into five temporal intervals t1 to t5. Here, itis also assumed that a predetermined single channel CH1 is used. Thenumber of controllers 2 communicable with the plurality of tags Tg areallocated for the channel CH1 in a predetermined cycle. For example, theallocation processor 112 allocates a controller A to a first temporalinterval t1, a controller B to a second temporal interval t2, acontroller C to a third temporal interval t3, a controller D to a fourthtemporal interval t4, and a controller E to a fifth temporal intervalt5.

The allocation processor 112 allocates the controllers A to E to thetemporal intervals t1 to t5, in the stated order, in each cycle C1.

In each of the plurality of temporal intervals, the communicationprocessor 113 causes a controller 2 to communicate with a plurality oftags Tg associated with the controller 2 by the association processor111, within that temporal interval. The following describes a specificexample of the communication method with reference to FIG. 8 .

In an example illustrated in FIG. 8 , in the channel CH1, a cycle C1 isassumed to be “200 ms”, and a time width for each of temporal intervalst1 to t5 is assumed to be “40 ms”. The communication processor 113outputs, to the controller A, a transmission instruction to transmittransmission data, in the first temporal interval t1 of the cycle C1.The transmission data is a beacon, for example.

Here, as illustrated in FIG. 9 , the transmission data includesinformation on a command (command information) to cause a tag Tg toexecute predetermined processing; and identification information(destination information) to identify the tag Tg to execute the command.Specifically, the transmission data includes destination information ofeach of a predetermined number of tags Tg; and command information forcausing each of the predetermined number of tags Tg to execute apredetermined command. For example, FIG. 9 illustrates an example oftransmission data transmitted by the controller A. The communicationprocessor 113 specifies five tags Tg (refer to FIG. 4 ) associated withthe five parts to be picked, from among the plurality of tags Tg (referto FIG. 5 ) associated with the controller A, and outputs, to thecontroller A, a transmission instruction to transmit transmission data,which includes the specified five tags 1 to 5 as the destination.

In other words, the communication processor 113 causes the controller Ato transmit transmission data to a predetermined number of tags Tg, fromamong the plurality of tags Tg associated with the controller A. Thecontroller A transmits the transmission data to the predetermined numberof tags Tg communicable with the controller A within the temporalinterval.

The controller A, when having obtained the transmission instruction fromthe management server 1, transmits the transmission data (refer to FIG.9 ) to all the tags Tg associated with the controller A (refer to FIG. 5), within the first temporal interval t1 (refer to FIG. 8 ).

Each tag Tg associated with the controller A, when having received thetransmission data, checks the destination included in the transmissiondata, and executes predetermined processing when a command destined toitself is included. For example, the tag 1, when having received thetransmission data including a command destined to itself to light thelamp button B1 (refer to FIG. 3 ), lights the lamp button B1 (refer toFIG. 3 ), because the command destined to itself is included. Inaddition, the tag 1, when having executed the command, transmits aresponse (acknowledgement) to the controller A. Similarly, each of thetags 2 to 5, when having received the transmission data including thesame command destined to itself, lights the lamp button B1 (refer toFIG. 3 ), because the command destined to itself is included, andtransmits a response (acknowledgement) to the controller A. Thecontroller A receives a response from each of the tags 1 to 5 (refer toFIG. 8 ). Here, the tags 1 to 5 perform transmission at an appropriatetiming so as not to interfere with one another, depending on what numbera command destined to itself is in the transmission data. In the presentembodiment, each tag Tg transmits an acknowledgement of a same size inthe order in which the command destined to itself is located in thetransmission data, and refrains from transmitting their acknowledgementfor a time period including the time required for the other tags Tg totransmit acknowledgement plus a predetermined margin, so thatinterference of the respective acknowledging signals is prevented.

Also in the present embodiment, a temporal interval is designed to havea tag data reception period R1 (refer to FIG. 9 ) after the transmissionof acknowledgements of all the five tags Tg, and a tag Tg, for which abutton function of a lamp is pushed, performs transmission in theCarrier Sense Multiple Access with Collision Avoidance (CSMA/CA) schemewithin the subsequent tag data reception period R1. The tag datareception period R1 illustrated in FIG. 9 is an uplink period (from thetag Tg to the controller 2) according to the CSMA/CA scheme.

Note that the acknowledgement is not limited to button push information,and may be how other user interfaces, if any, are operated. In addition,a configuration is possible in which, if a tag Tg has a sensor function,the tag Tg autonomously performs the transmission when the measuredvalue satisfies a predetermined condition.

When the controller A transmits the transmission data to the tags 1 to 5in the first temporal interval t1 (40 ms) in the cycle C1 (200 ms) andwhen the command execution of the tags 1 to 5 completes, thecommunication processor 113 outputs, to the controller B, a transmissioninstruction to transmit transmission data (refer to FIG. 8 ), in thenext second temporal interval t2 in the cycle C1 (200 ms). Thetransmission data includes the destinations and commands for the tags 6to 10.

Each tag Tg associated with the controller B, when having received thetransmission data, checks the destination included in the transmissiondata, and executes predetermined processing when a command destined toitself is included. For example, the tag 6, when having received thetransmission data including a command destined to itself to light thelamp button B1 (refer to FIG. 3 ), lights the lamp button B1 (refer toFIG. 3 ), because the command destined to itself is included. Inaddition, the tag 6, when having executed the command, transmits aresponse (acknowledgement) to the controller B. Similarly, each of thetags 7 to 10, when having received the transmission data including thesame command destined to itself, lights the lamp button B1 (refer toFIG. 3 ), because the command destined to itself is included, andtransmits a response (acknowledgement) to the controller B. Thecontroller B receives a response from each of the tags 6 to 10.

When the controller B transmits the transmission data to the tags 6 to10 in the second temporal interval t2 (40 ms) in the cycle C1 (200 ms)and when the command execution of the tags 6 to 10 completes, thecommunication processor 113 outputs, to the controller C, a transmissioninstruction to transmit transmission data, in the next third temporalinterval t3 in the cycle C1 (200 ms). The transmission data includes thedestinations and commands for the tags 11 to 15 (refer to FIG. 8 ).

Each tag Tg associated with the controller C, when having received thetransmission data, checks the destination included in the transmissiondata, and executes predetermined processing when a command destined toitself is included. For example, the tag 11, when having received thetransmission data including a command destined to itself to light thelamp button B1 (refer to FIG. 3 ), lights the lamp button B1 (refer toFIG. 3 ), because the command destined to itself is included. Inaddition, the tag 11, when having executed the command, transmits aresponse (acknowledgement) to the controller C. Similarly, each of thetags 12 to 15, when having received the transmission data including thesame command destined to itself, lights the lamp button B1 (refer toFIG. 3 ), because the command destined to itself is included, andtransmits a response (acknowledgement) to the controller C. Thecontroller C receives a response from each of the tags 11 to 15 (referto FIG. 8 ).

When the controller C transmits the transmission data to the tags 11 to15 in the third temporal interval t3 (40 ms) in the cycle C1 (200 ms)and when the command execution of the tags 11 to 15 completes, thecommunication processor 113 outputs, to the controller D, a transmissioninstruction to transmit transmission data, in the next fourth temporalinterval t4 in the cycle C1 (200 ms). The transmission data includes thedestinations and commands for the tags 16 to 20.

Each tag Tg associated with the controller D, when having received thetransmission data, checks the destination included in the transmissiondata, and executes predetermined processing when a command destined toitself is included. For example, the tag 16, when having received thetransmission data including a command destined to itself to light thelamp button B1 (refer to FIG. 3 ), lights the lamp button B1 (refer toFIG. 3 ), because the command destined to itself is included. Inaddition, the tag 16, when having executed the command, transmits aresponse (acknowledgement) to the controller D. Similarly, each of thetags 17 to 20, when having received the transmission data including thesame command destined to itself, lights the lamp button B1 (refer toFIG. 3 ), because the command destined to itself is included, andtransmits a response (acknowledgement) to the controller D. Thecontroller D receives a response from each of the tags 16 to 20 (referto FIG. 8 ).

When the controller D transmits the transmission data to the tags 16 to20 in the fourth temporal interval t4 (40 ms) in the cycle C1 (200 ms)and when the command execution of the tags 16 to 20 completes, thecommunication processor 113 outputs, to the controller E, a transmissioninstruction to transmit transmission data, in the next fifth temporalinterval t5 in the cycle C1 (200 ms). The transmission data includes thedestinations and commands for the tags 21 to 25.

Each tag Tg associated with the controller E, when having received thetransmission data, checks the destination included in the transmissiondata, and executes predetermined processing when a command destined toitself is included. For example, the tag 21, when having received thetransmission data including a command destined to itself to light thelamp button B1 (refer to FIG. 3 ), lights the lamp button B1 (refer toFIG. 3 ), because the command destined to itself is included. Inaddition, the tag 21, when having executed the command, transmits aresponse (acknowledgement) to the controller E. Similarly, each of thetags 22 to 25, when having received the transmission data including thesame command destined to itself, lights the lamp button B1 (refer toFIG. 3 ), because the command destined to itself is included, andtransmits a response (acknowledgement) to the controller E. Thecontroller E receives a response from each of the tags 21 to 25 (referto FIG. 8 ).

When the controller E transmits the transmission data to the tags 21 to25 in the fifth temporal interval t5 (40 ms) in the cycle C1 (200 ms)and when the command execution of the tags 21 to 25 completes, thecommunication processor 113 outputs, again to the controller A, atransmission instruction to transmit transmission data, in the firsttemporal interval t1 in the next cycle C1 (200 ms). The transmissiondata includes the destinations and commands for the tags 1 to 5.

Each tag Tg associated with the controller A, when having received thetransmission data, checks the destination included in the transmissiondata, and executes predetermined processing when a command destined toitself is included. For example, the tag 1, when having received thetransmission data including a command destined to itself to light thelamp button B1 (refer to FIG. 3 ), lights the lamp button B1 (refer toFIG. 3 ), because the command destined to itself is included. Inaddition, the tag 1, when having executed the command, transmits aresponse (acknowledgement) to the controller A. Similarly, each of thetags 2 to 5, when having received the transmission data including thesame command destined to itself, lights the lamp button B1 (refer toFIG. 3 ), because the command destined to itself is included, andtransmits a response (acknowledgement) to the controller A. Thecontroller A receives a response from each of the tags 1 to 5 (refer toFIG. 8 ).

As described above, the communication processor 113, in each of theplurality of temporal intervals, causes a controller 2 and a pluralityof tags Tg associated with the controller 2 to communicate with eachother, within that temporal interval. In addition, the communicationprocessor 113 outputs, to each of the plurality of controllers 2, thetransmission instruction to transmit transmission data, in the order ofthe temporal intervals. Accordingly, each of the controllers A to Ecommunicates with the tag Tg controlled by each of the controllers A toE, in the order of the temporal intervals t1 to t5.

For example, in the first temporal interval t1, the controller Atransmits the transmission data to five tags 1 to 5, among the pluralityof tags Tg associated with the controller A; and then in the secondtemporal interval t2 subsequent to the first temporal interval t1, thecontroller B transmits the transmission data to five tags 6 to 10, amongthe plurality of tags Tg associated with the controller B.

In addition, in the first temporal interval t1, the controller Atransmits the transmission data to the tags 1 to 5, and the controller Areceives a response thereto from the tags 1 to 5. Then in the secondtemporal interval t2, the controller B transmits the transmission datato the tags 6 to 10.

Here, the controlling part 11 performs processing to synchronize (timesynchronization) the management server 1 and each controller. Inaddition, each controller 2 executes processing to synchronize (timesynchronization) with the corresponding tags Tg. As a result, eachcontroller 2 transmits transmission data to a tag Tg in a predeterminedcycle (e.g., 200 ms), and each tag Tg receives the transmission data ina predetermined cycle (e.g., 200 ms). For example, each tag Tg startsactivation in preparation for a reception time at which the transmissiondata is received, and starts receiving the transmission data at thereception time. Each tag Tg completes the reception processing by atransmission completion time at which transmission of the transmissiondata completes in the controller 2, and performs time synchronizationafter completion of the reception processing. Each tag Tg waits (powersaving) by setting a timer until the reception time of the transmissiondata.

Note that the time synchronization between each controller 2 may beautonomously performed between each controller 2 according to the IEEE1588 Precision Time Protocol, for example. In addition, thecommunication processor 113 may notify each controller 2 of the cycle C1and the temporal intervals t1 to t5, and control each controller 2 toperform communication at the timing illustrated in FIG. 7 .

Communication Processing

The following describes an exemplary procedure of communicationprocessing executed in the communication system 10, with reference toFIG. 10 .

Note that the present disclosure can be interpreted as disclosure of acommunication method in which one or a plurality of steps incommunication processing are executed, and one or a plurality of thesteps included in the communication processing described herein may beomitted as necessary. The order of execution of the steps in thecommunication processing may differ to the extent that the similareffects are obtainable. Furthermore, the following takes an example inwhich the steps in the communication processing are executed by themanagement server 1 and the controller 2. However, the presentdisclosure can include, as another embodiment, such a communicationmethod in which a plurality of processors execute steps in thecommunication processing in a distributed manner.

The following takes an example of the communication method describedabove with reference to FIGS. 8 and 9 . The controlling part 11 of themanagement server 1 uses a predetermined channel CH1 to output atransmission instruction of transmission data (refer to FIG. 8 ) to eachof the controllers A to E having been allocated to five temporalintervals t1 to t5 (40 ms each), where the five temporal intervals t1 tot5 result from time-division of the predetermined cycle (200 ms).

First, when a first cycle (N=1) starts (S1), in step S2, the controllingpart 11 determines whether the first temporal interval t1 has started.When the first temporal interval t1 has started (S2: Yes), in step S3,the controlling part 11 outputs, to the controller A, a transmissioninstruction to transmit transmission data. The controller A, havingobtained the transmission instruction, transmits the transmission dataincluding tags Tg to execute the command (e.g., tags 1 to 5) as adestination, to all the tags Tg associated with the controller A (referto FIG. 5 ).

Next, in step S4, the controlling part 11 determines whether responses(acknowledgement) of the tags Tg have been received. For example, whenthe tags 1 to 5 receive the transmission data, execute a command(lighting command) and transmit a response to the controller A, thecontroller A transmits the received responses to the management server1. As a result, the controlling part 11 of the management server 1receives the responses. When the controlling part 11 receives theresponses (S4: Yes), the processing proceeds to step S5.

In step S5, the controlling part 11 determines whether the secondtemporal interval t2 has started. When the second temporal interval t2has started (S5: Yes), in step S6, the controlling part 11 outputs, tothe controller B, a transmission instruction to transmit transmissiondata. The controller B, having obtained the transmission instruction,transmits the transmission data including tags Tg to execute the command(e.g., tags 6 to 10) as a destination, to all the tags Tg associatedwith the controller B (refer to FIG. 5 ).

Next, in step S7, the controlling part 11 determines whether responsesof the tags Tg have been received. For example, when the tags 6 to 10receive the transmission data, execute a command (lighting command) andtransmit a response to the controller B, the controller B transmits thereceived responses to the management server 1. As a result, thecontrolling part 11 of the management server 1 receives the responses.When the controlling part 11 receives the responses (S7: Yes), theprocessing proceeds to step S8.

In step S8, the controlling part 11 determines whether the thirdtemporal interval t3 has started. When the third temporal interval t3has started (S8: Yes), in step S9, the controlling part 11 outputs, tothe controller C, a transmission instruction to transmit transmissiondata. The controller C, having obtained the transmission instruction,transmits the transmission data including tags Tg to execute the command(e.g., tags 11 to 15) as a destination, to all the tags Tg associatedwith the controller C (refer to FIG. 5 ).

Next, in step S10, the controlling part 11 determines whether responsesof the tags Tg have been received. For example, when the tags 11 to 15receive the transmission data execute a command (lighting command) andtransmit a response to the controller C, the controller C transmits thereceived responses to the management server 1. As a result, thecontrolling part 11 of the management server 1 receives the responses.When the controlling part 11 receives the responses (S10: Yes), theprocessing proceeds to step S11.

In step S11, the controlling part 11 determines whether the fourthtemporal interval t4 has started. When the fourth temporal interval t4has started (S11: Yes), in step S12, the controlling part 11 outputs, tothe controller D, a transmission instruction to transmit transmissiondata. The controller D, having obtained the transmission instruction,transmits the transmission data including tags Tg to execute the command(e.g., tags 16 to 20) as a destination, to all the tags Tg associatedwith the controller D (refer to FIG. 5 ).

Next, in step S13, the controlling part 11 determines whether responsesof the tags Tg have been received. For example, when the tags 16 to 20receive the transmission data, execute a command (lighting command) andtransmit a response to the controller D, the controller D transmits thereceived responses to the management server 1. As a result, thecontrolling part 11 of the management server 1 receives the responses.When the controlling part 11 receives the responses (S13: Yes), theprocessing proceeds to step S14.

In step S14, the controlling part 11 determines whether the fifthtemporal interval t5 has started. When the fifth temporal interval t5has started (S14: Yes), in step S15, the controlling part 11 outputs, tothe controller E, a transmission instruction to transmit transmissiondata. The controller E, having obtained the transmission instruction,transmits the transmission data including tags Tg to execute the command(e.g., tags 21 to 25) as a destination, to all the tags Tg associatedwith the controller E (refer to FIG. 5 ).

Next, in step S16, the controlling part 11 determines whether responsesof the tags Tg have been received. For example, when the tags 21 to 25receive the transmission data, execute a command (lighting command) andtransmit a response to the controller E, the controller E transmits thereceived responses to the management server 1. As a result, thecontrolling part 11 of the management server 1 receives the responses.When the controlling part 11 receives the responses (S16: Yes), theprocessing returns to step 51.

When the processing has returned to step 51, a second cycle (N=2)starts, and in step S2, the controlling part 11 determines whether thefirst temporal interval t1 has started. When the first temporal intervalt1 has started (S2: Yes), in step S3, the controlling part 11 outputs,to the controller A, a transmission instruction to transmit transmissiondata. The controller A, having obtained the transmission instruction,transmits the transmission data including tags Tg to execute the command(e.g., tags 1 to 5) as a destination, to all the tags Tg associated withthe controller A (refer to FIG. 5 ). The processing hereafter is similarto those described above. In this way, the communication system 10executes the communication processing.

As described so far, the communication system 10 according to thepresent embodiment is a communication system in which a plurality ofcontrollers 2 (master station) wirelessly communicate with a pluralityof tags Tg (slave station) in a predetermined cycle. The communicationsystem 10 associates each of the plurality of tags Tg with one of theplurality of controllers 2. The communication system 10 also associateseach of the plurality of controllers 2 with one of a plurality oftemporal intervals (time slot) intervals (time slot) resulting fromtime-dividing the predetermined cycle in a predetermined channel. Ineach of the plurality of temporal intervals, the communication system 10causes a controller 2 to communicate with the plurality of tags Tgassociated with the controller 2, within that temporal interval.

In the above-described configuration, each controller 2 uses radio wavesonly in the temporal interval (40 ms) out of the cycle (e.g., 200 ms).In addition, by allocating (adjusting) the time during which thecontrollers 2 are allowed to use the radio waves, to avoid overlappingthereamong, the plurality of controllers 2, up to the maximum of fivecontrollers, can share a single channel (CH1). As a result, even in thecase of FIG. 11 where the communication areas AR overlap with oneanother, a multitude of controllers 2 can be provided. For example, ifthe number of frequency channels is 20 in an area where radio wavesinterfere with one another, a hundred controllers 2 can be provided,which is five times the number of channels.

Depending on the factory layouts or the types of lines, there are casesin which channels are desirably allocated to the controllers 2, inconsideration of the maximum number of channels that can be sharedbetween the controllers 2. In such a case, such a display screen (UI)may be provided, in which the numbers for the controllers (e.g., 1 to64) can be set and mapped on a table having the vertical linerepresenting a time slot (slot number) and the horizontal linerepresenting a channel (frequency channel) as illustrated in FIG. 12 .In other words, the controlling part 11 may display, to be visuallyidentifiable, predetermine channels and predetermined temporalintervals, to which a plurality of controllers 2 (master station) areallocated.

In addition, the transmission data includes destination information of aplurality of tags Tg. According to this configuration, each of aplurality of controllers 2 can use a single channel to communicate witha plurality of tags Tg, in each temporal interval allocated to theplurality of controllers 2, in each cycle. Therefore, a multitude oftags Tg can be provided in a wide range. In addition, a communicationamount increases in the communication system 10. As a result, amultitude of tags Tg can be provided by ensuring high-speedresponsiveness in communication of the controllers 2 and the tags Tg.

In the communication system 10 according to the present embodiment, aplurality of controllers 2 (master station) mutually synchronize time,and perform communication within the temporal interval allocated by theallocation processor 112. The plurality of controllers 2 may be coupledwith one another by wired communication.

When data in the tag Tg (slave station) is to be transmitted, thecommunication processor 113 causes the data to be transmitted to acontroller 2 associated with the tag Tg, within the temporal intervalallocated to the controller 2.

The data in the tag Tg to be transmitted is data observed in the tag Tg.In addition, the data observed in the tag Tg is data corresponding tohow the user interface of the tag Tg is operated.

The present disclosure is not limited to the above-described embodiment,and may be embodiments as described follows. In an example, thecommunication system 10 may include a plurality of channels. In such acase, the allocation processor 112 allocates the plurality ofcontrollers 2 respectively to the plurality of temporal intervals ineach channel. As a result, five controllers A to E share a channel CH1,five controllers F to J share a channel CH2, five controllers K to Oshare a channel CH3, five controllers P to T share a channel CH4, andfive controllers U to Y share a channel CH5. As in the above-describedembodiment, each controller 2 communicates with a plurality of tags Tgin each of the plurality of temporal intervals resulting fromtime-dividing a predetermined cycle. According to this configuration,the providable number of controllers 2 can be increased depending on thenumber of available channels. As a result, even more tags Tg can beprovided.

In the above-described embodiment, a cycle of 200 ms is divided intofive slots of 40 ms. However, this is merely an example; and the cycle,the number of division, and the slot time may be set as appropriate, bytaking into consideration the time responsiveness, the powerconsumption, the number of slave stations, the number of availablefrequency channels, the communication speed, etc. which are required foreach intended use.

Also in the above-described embodiment, the management server 1(mediating station) controls a plurality of controllers 2. However, inanother embodiment, a specific controller 2, from among the controllers2, may also function as the management server 1. In such a case, thespecific controller 2 functions as a master controller, and the othercontrollers 2 function as slave controllers. The master controllerexecutes allocation processing to allocate each of the plurality ofslave controllers to one of the plurality of temporal intervals in apredetermined channel, and communication processing to cause each of theslave controllers to communicate with the plurality of tags Tg in eachof the plurality of temporal intervals. The master controller transmitsthe transmission data to each slave controller in the order of thetemporal intervals. Note that the controller 2 to function as the mastercontroller may be interchanged, as necessary, depending on thecommunication state in the entire communication system 10.

As described above, the communication system according to the presentdisclosure may be configured by the entire communication system 10(refer to FIG. 1 ) which includes the management server 1, thecontroller 2, and the tag Tg; may be configured by the management server1 and the controller 2; or may be configured solely by the managementserver 1 or solely by the controller 2.

It is to be understood that the embodiments herein are illustrative andnot restrictive, since the scope of the disclosure is defined by theappended claims rather than by the description preceding them, and allchanges that fall within metes and bounds of the claims, or equivalenceof such metes and bounds thereof are therefore intended to be embracedby the claims.

1. A communication system in which a plurality of master stationswirelessly communicate with a plurality of slave stations in apredetermined cycle, each of the plurality of slave stations beingassociated with one of the plurality of master stations, wherein thecommunication system comprises: an allocation circuit that allocates theplurality of master stations respectively to a plurality of temporalintervals resulting from time-division of the predetermined cycle, in apredetermined channel; and a communication circuit that, in each of theplurality of temporal intervals, causes the master station tocommunicate with a plurality of slave stations associated with themaster station, within that temporal interval.
 2. The communicationsystem according to claim 1, wherein the plurality of master stationsmutually synchronize time, and perform communication within a temporalinterval allocated by the allocation circuit.
 3. The communicationsystem according to claim 1, wherein the plurality of master stationsare coupled with one another by wired communication.
 4. Thecommunication system according to claim 1, wherein when data in a slavestation is to be transmitted, the communication circuit causes the datato be transmitted to a master station associated with the slave station,within a temporal interval allocated to the master station associatedwith the slave station.
 5. The communication system according to claim4, wherein the data in the slave station to be transmitted is dataobserved in the slave station.
 6. The communication system according toclaim 5, wherein the data observed in the slave station is datacorresponding to how a user interface of the slave station is operated.7. The communication system according to claim 1, wherein thecommunication circuit causes a first master station among the pluralityof master stations to transmit transmission data to a predeterminednumber of slave stations from among a plurality of slave stationsassociated with the first master station.
 8. The communication systemaccording to claim 7, wherein the plurality of slave stationsrespectively transmit an acknowledgement in a time-exclusive manner tothe first master station associated with the plurality of slavestations, within a temporal interval allocated to the first masterstation.
 9. The communication system according to claim 7, wherein thefirst master station transmits the transmission data to thepredetermined number of slave stations communicable with the firstmaster station within the temporal interval.
 10. The communicationsystem according to claim 7, wherein the transmission data includes:destination information of each of the predetermined number of slavestations; and command information for causing each of the predeterminednumber of slave stations to execute a predetermined command.
 11. Thecommunication system according to claim 7, wherein the communicationcircuit outputs, to each of the plurality of master stations, atransmission instruction to transmit the transmission data, in an orderof the temporal intervals.
 12. The communication system according toclaim 7, wherein after the first master station transmits thetransmission data to the predetermined number of slave stations fromamong the plurality of slave stations associated with the first masterstation in a first temporal interval allocated to the first masterstation, a second master station which is different from the firstmaster station transmits the transmission data to a predetermined numberof slave stations from among a plurality of slave stations associatedwith the second master station in a second temporal interval which issubsequent to the first temporal interval.
 13. The communication systemaccording to claim 12, wherein after the first master station transmitsthe transmission data to the predetermined number of slave stations inthe first temporal interval and the first master station receives aresponse from the predetermined number of slave stations, the secondmaster station transmits the transmission data to the predeterminednumber of slave stations.
 14. The communication system according toclaim 7, wherein the number of the master stations communicable with theplurality of slave stations in the predetermined cycle, are allocated tothe predetermined channel.
 15. The communication system according toclaim 1, wherein the communication system uses a plurality of channels,and the allocation circuit allocates the plurality of master stationsrespectively to the plurality of temporal intervals in each of thechannels.
 16. The communication system according to claim 1, whereinpredetermined channels and predetermined temporal intervals to which theplurality of master stations are respectively allocated are displayed tobe visually identifiable thereamong.
 17. A communication method in whicha plurality of master stations wirelessly communicate with a pluralityof slave stations in a predetermined cycle, each of the plurality ofslave stations being associated with one of the plurality of masterstations, the communication method causing one or a plurality ofcircuits to perform: allocating the plurality of master stationsrespectively to a plurality of temporal intervals resulting fromtime-division of the predetermined cycle, in a predetermined channel;and causing the master station to, in each of the plurality of temporalintervals, communicate with a plurality of slave stations associatedwith the master station, within that temporal interval.
 18. Anon-transitory computer-readable recording medium recording therein acommunication program by which a plurality of master stations wirelesslycommunicate with a plurality of slave stations in a predetermined cycle,each of the plurality of slave stations being associated with one of theplurality of master stations, the communication program causing one or aplurality of circuits to perform: allocating the plurality of masterstations respectively to a plurality of temporal intervals resultingfrom time-division of the predetermined cycle, in a predeterminedchannel; and causing the master station to, in each of the plurality oftemporal intervals, communicate with a plurality of slave stationsassociated with the master station, within that temporal interval.